Process of concentrating ores.



UNITED STATES PATENT OFFICE.

PROCESS OF CONCENTRATING ORES.

Specification of Letters Patent.

Patented Nov. 21, 1905.

Application filed February 7, 1905. Serial No. 244,640.

To aZl whom it may concern.-

Be it known that I, WALTER l\/IURRAY SAN- DERS, a citizen of the UnitedStates, residing at Iola, in the county of Allen and State of Kansas,haveinvented certain new and useful Improvements in Processes ofConcentrating Ores, of which the following is a specification.

This invention is a process of concentrating ores by means of non-acidsolutions.

It has heretofore been proposed to separate sulfid ores from theirgangue by means of acids or acid solutions, the acid reacting with thesulfid to liberate hydrogen sulfid, the adhering bubbles of which arecapable of carrying the finely-divided ore to the surface of the liquid.

I have discovered that sulfid ores, and particularly zinc sulfid, arecapable of reacting with certain non-acid solutions to liberate hydrogensulfid, which serves to sustain and transport the particles of ore. Forthe separation of zinc sulfid from a gangue containing fluor-spar,barite, silica, rhodonite, &c., I have successfully used a neutral orsomewhat basic solution containing aluminium sulfate, the solution beingpreferably heated and having a specific gravity of 1.15 to 1.25. Suchsolution may be conveniently prepared by dissolving low-grade bauxite insulfuric acid. Non-acid solutions of other of the socalled earthmetals-as, for instance, ferric sulfatemay be used with good results.The term earth metals is here used to indicate the metals of thealuminium, iron, and chromium group. Such non-acid solutions possessseveral important general advantages over the acids or acid solutionsheretofore used. The liquid remains remarkably clear, and by virtue ofthe viscosity of the solution and its high surface tension the particlesof ore may be sustained in the liquid for avery considerable period.This, together with the non-corrosive character of the liquid, permits awide latitude of design in the construction and of choicein thematerials of the separator.

The earth-metal sulfate solutions possess certain special advantages forthe concentration of ores containing zinc sulfid. I have found that forthe best separation of Zinc sulfid the ores should be quite finelypulverized, which under ordinary conditions would involve serious lossesin roasting. The earthmetal oxid, however, which results from thedecomposition during roasting of the residual sulfate, acts as aneffective binder for the fine ores and reduces the dust loss to aminimum.

Further, the residual oxid is non-corrosive toward the zinc retorts inthe final distillation and often exerts a distinctly-beneficial eflect,whereas such compounds as salt-cake, which are reducible to sulfids, areunsuited for use by reason of their corrosive action on the retorts.

I do not limit myself to any particular form of apparatus for thetreatment of ore nor to any specific means for the separation of theconcentrate.

I employ the term ore as including tailings, residues, or concentrateswhich. are capable of reacting with non-acid solutions of the characterdescribed to evolve a gas capable of raising or sustaining the dividedmate rial in the solution.

I claim 1. The method of concentrating ore, which consists in subjectingit to a non-acid solution capable of reacting with evolution of gas, andcollecting such particles as are sustained by the evolved gas,substantially as described.

2. The method of concentrating ore, which consists in subjecting it to anon-acid solution containing a sulfate of an earth metal, and collectingsuch particles as are sustained by the evolved gas, substantially asdescribed.

3. The method of concentrating sulfid ores, which consists in subjectingthem to a nonacid solution containing a sulfate of an earth metal, andcollecting such particles as are sus tained by the evolved gas,substantially as described.

4.. The method of concentrating zinc-sulfid ore, which consists insubjecting it to a nonacid solution containing a sulfate of an earthmetal, and collecting such particles as are sustained by the evolvedgas, substantially as described.

In testimony whereof I affiX my signature in presence of two witnesses.

WALTER MURRAY SANDERS.

Witnesses:

E. G. DANFORTi-I, A. W. HAIGLER.

